In the process of continuously casting steel slab, molten metal is poured into the open upper end of a box-like mold, within which the metal is cooled for continuously exiting through the open bottom end in a slab-like form. An example of a mold used for this process is illustrated in my prior U.S. Pat. No. 3,978,910 issued Sept. 7, 1976 and also in my prior U.S. Pat. No. 3,964,727 issued June 22, 1976.
In such molds, the molten metal adjacent the interior walls of the mold is chilled and a thin skin is formed on the metal. The interior of the metal slab remains molten. Thus, as the metal exits from the lower end of the mold, it is in the form of a relatively thin casing or skin of solidified metal surrounding an interior core of molten metal. The continuously moving slab is then cooled further until ultimately it is solidified throughout.
In a typical continuous casting operation, the metal is cast downwardly into the mold which basically is like a vertical tube of approximately rectangular cross section, and as the metal exits from the lower end of the tubular mold, it is curved, gradually, until it takes a full 90.degree. bend at some distance from the mold, so that the continuous slab becomes horizontal for cutting and handling at the point where the metal is solidified.
A problem in continuously casting metal in the manner described above, is that as the metal exits from the lower end of the casting mold, its skin is sufficiently fragile that it may distort or bulge or rupture. Hence, it is desirable to cool such skin and thicken it as rapidly as possible to the point where it is reliably self-sustaining.
Prior cooling systems involved flowing water either upon the slab or through cooled rollers or plates for cooling the slab below the mold. However, such cooling has not been fully satisfactory to alleviate the problems caused by the relatively thin skinned slab emerging from the lower end of the mold in a fragile condition prior to further cooling.
Hence, the invention herein relates to an improved type of cooling system incorporated with the mold to alleviate the foregoing problem.